ios学习笔记
1.对于autorelease的理解
Each thread in a Cocoa application maintains its own stack of autorelease pool blocks.(Advanced Memory Management Programming Guide:Using Autorelease Pool Blocks)
通过这句话,我们可以看出
- autorelease pool 是栈的形式,and autorelease pool blocks can be nested
- 主线程中也有自己的autorelease pool,这又牵扯出run loop。实际上,每次执行一次runloop时,就会释放当前autorelease pool中的对象。run loop 是ios中与线程有关的一个基础架构,用于处理事件循环的。
2.对于runtime的理解
The objective-c language defers as many decisions as it can from compile time and link time to runtime.
这意味着oc不仅需要一个编译器,还需要一个运行时系统,来执行编译过的代码。这个运行时系统对于oc来说扮演着操作系统的角色。
- In Objective-C, messages aren't bound to method implentationss until runtime.
3.对于CALayer的理解
Layer是Core Animation的核心。
Layers are data objects that manage content provided by your app。
A layer's content contains of a bitmap containing the visual data you want to display.有3种方法来设置它的content
- 直接将一个对象分配给layer的content属性
- 为layer指定个delegate对象,来delegate来draw它的content:displayLayer: 和drawLayer: inContent:
- 子类一个layer,重写它的drawing方法:重写display或者drawInContext方法